Structural material



' A. scHMm STRUCTURAL MATERIAL Aprii 15, @4 1.

Filed June 26, 1957 J7? ven for:

flgf'redlscbm id Patented Apr- 15, v

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This invention relates .to n w; t bular. lislht structural material.

A light strucamu material which is to beju'sed particularly suitable;mum itsslilht combus-- rtibility and it's property I of beingwaterproof.

A primarily for the construction'ot air-shipsl'and aeroplanes has tosatisfy a "number ,oi'diiierent requirements. Inthe flrstplaceit'mu'sthe of 'zreat strength and lightweight and itimustbe- 7 ca ble beingior'many diil'erent kinds 1 s v s is a pa amorintsgdtjtromffitd 2aresuiiicient dependoi constructions and must be veryv lresistant toatmospheric influences." Th'ese; requirements have notbeensatistaetorily met by the structural v materials,such-asjwoodandmetals; amenn ve hitherto been used; A

which must satisiled is that-the structures 7 can be rapidly constructedfrom the material,

second and more 7' important larly. advantateoustofladdj'smallquantities; oi

"Nitrocelllfloa also has been ioundto be very suit-- able particularlyi!some acetyl cellulose issdded to' itin orderf or eiiminateits .mabiiity.a solventaliscetone;methyljslcohoi I d, the k an .h l msli yed. and; 1??

'ing' on the viscosity whichv occurs. It particuacetic acid, iormic,acid g t the liketojjthe solvent x-since a better swellinz end morerapid 'adherence a is thereby'obtainedg. 1' .The individualf p I w 1 mltubular elements oizthe la e ordiflerin:

that is to say they can be firmly united in'a short time, so that themain cost otan aircraft'is not, as previously. the cost or the workinghours necessary for its construction; while that oft-the structuralmaterial itself is relativelyvsmall.

cross-section, for example also'bi conicsleross section; ean bestuckjtozether indifferent ways.

'ior examplea pnil alongitheir or a a v 2 {,nected either one intoanother or by means of The present invention solve'sthls probiemby asthe structural material,,circular,.'.noncircular or polygonal tubularelements which are made of a-cellulose derivative, or ofpaperorceliulose fibrous material whichicontains elther su periiciailyor throughoutsomuch cellulose de'riv 'I' r, ,i a s.

T t e jiwhicmm w m iwhs am i another or. bycross pieces or are' stuckto'lether.

' form-a unit by the use otasol'vent'. The lsol'v'ent' 'rnay ormay notcontain a cellulose 'deriyatiye;';j

' The of cellulose derivatives audio! paper and .iibrous materialsimpregnated p or saturated The tubular elements, however; can concalstrensth,, The llabbrtaz'it'ieature "is the connections 'by'jnieans Ifoiiaselvent I which may or may not contain aelluiosederitativei'inbundies-can'a'lso be e'nvelopedjby a smile enclosing of cellulose,derivative..; f 0l' I 1 example a sheetot cellulose acetate or by a papr or fibrous material.--ior eiample a sheet of paper,

ween is impreana ted r N ted-with cellulose f derivative. in which caseap rticull-fly desirable light'str'uctural material which canbeused-lior with such derivatives for thejmanufactur'e of separate lighttubular structural materials 'iswell known. The present invention,howeveni makes a use of the possibility oi'rapidiy and flrmly'fstickin:together and building-up'ic'ellulosi jderiyamany 'diiierent purposes isobthree with the use 01' solvents tor rapidly"'assema v bling' to iormiabuilt-up unit apluralityjoi tu a bularelements which consist ofcellulosederivatlves. or ofpapencellulosic or other fibrous, inaterials,which are impregnated 'or him such derivatives.

Instead oi! using' paperor'celluiosic flbrous'vma- Ihe builtup unitwhich" is @iormed represents an ideal light structural part'.-

terials, other naturalor artificial textile flbibua materials; asbestos,animal fibrous materials and so i'orth as well as fabrics or otherproduets ma de from such fibrous materials can be employed.

Materials having particularly good properties are obtained if. forexample, metal wires ormetal iabric are embedded or cast in the saidstructural material.

' The individual rtubes can be time bycasting.

pressing, winding and sticking together rolls or sheets or in anyothersuitable manner. As the cellulose derivatives any known derivativescan the tubesiasfweil 'ss that between the tubes and any envelope-whichma'yfbe provided maybe -wno11y or partly filled with a'liahtjporoussubstance. for example solidified glue i'oam'. by which means the bettersupportedon,

the inside and the liability to bend is reduced. Other suitable means beemployed for thesamepurpose; The light, structuraijpartsjwhich have beenmade-{in acwrdance with the "invention; in one or other or forms whichhavebee'n described have the advantagesthat notonly. dojtheypos sessgreat strength and arezoi lightweight but they can'be built' up in arelatively short time .to i'orm the most complicated structure'sand'seta very quicklmwhereas the methods of sticking together woodland othermaterials whichahave previously been employed arecompiicated andexpensive. Further, in these light structural materials any tendency ofthe cellulose and "cellulose derivatives to absorb water is eliminatedhowever to add pigments to the cellulose derivatives, and preferablypigments having great covering power such as, for example, titaniumwhite, lithopone and the like, for example in amounts of '5 to 25%calculated on the quantity of the cellulose derivative. The pigment canbe added to the cellulose derivative which constitutes the material,orto the derivatives with which the fibrous materials 'are'impregnatedor saturated, or to the derivatives which are contained in the solventused for sticking the individual tubes together, or to the derivativeswith which the finished structural parts are coated. It has beenunexpectedly observed that by this means the cellulose derivative iscaused to harden or become horny-and this has anextremely beneficialeffect on the properties of the structural material, probably by reasonof colloidal combination. This eflect is'the more pronounced the greaterthe covering power of the pigment is.

. Finally, it has also been found that it is advantageous to treat thecellulose present in the fibrous materials with weak acids,'for exampleacetic acid, formic acid and the like, since this treatment also has abeneficial effect on the properties of the structural material.

Various light structural'parts made in accordance with the inventionare'illustrated diagrammatically and by way of example'in theaccompanying drawing.

Fig. 1 shows a light structural part which con- 'sists of the tubes I to6' which are made of sheet cellulose derivative or of a sheet of'paperimpregnated withcellulose derivative. The individual tubes I to '8 arestuck togetheralong lines running along their periphery, by means oface-v tone or anothersolvent, which may or may not contain a cellulosederivative, so as to form the unit illustrated in the figure.

Fig. 2 shows a light structural part similar to that shown in Fig. 1 andconsisting of a number of tubes-I to 8 which have beenstuck together.The part shown in this figure differs from that shown in Fig. 1 in thatthe bundle of tubes, .after having been stucktogether, is additionallyenveloped by a jacket 1 consisting of sheet'cellulose' acetate or of asheet of paper impregnated with a cellulose derivative. This envelope isstuck on in a similar manner and its surface can be coated with awaterproof varnish or with a mixture-of a cellulose derivative with apigment.

Fig. 3 shows a further form of construction in which the, lightstructural part is formed from two tubes 8 and 9 which are stucktogether at It to form aT-piece, a solvent which may or previouslydescribed are connected by tubular cross pieces l4, l5 and I! which arestuck to them. The structural unit which is thereby obmay not contain acellulose derivative'being em- I .of a cellulose derivative.

assess? and in the tubes ll to II.

Fig. 5 shows a form which is specially suitable. for aircraftconstruction in which the tubes I I to 2 I, which have been made in themanner previously described and are to form the main beam, are conical.The tubes are connected on the triangle principle in order to obtain,great strength. This triangular tubular pyramid is braced at suitabledistances apart by the crosspieces 22 which also consist of tubes madeof cellulose derivatives or fibrous materials impregnated or saturatedwith cellulose derivatives. The

cross-pieces 22 are stuck tothe tubes II to II' by means of a solvent towhich a cellulose derivative may or may not be added.

I claim:

1. A light tubular structural unit comprising plurality of parallellydisposed, tubular elements of circular cross section essentiallycomposed of a cellulou derivative, said tubular elements beingassociated together in the form of a bundle and being adhesively unitedat their surfaces of contact with each other with the aid of a solutionof a cellulose derivative.

2. A light tubular structural unit comprising a plurality of parallellydisposed, tubular ele- .ments of circular cross section essentiallycomposed of "a cellulose derivative reinforced with fibrous material,said tubular elements being associated together inthe form of' a bundleand being adhesively united at their surfaces of contact with each otherwith the aid of a solution 3. A light tubular structural unit comprisinga plurality of parallelly disposed, tubular ele- :ments of circularcross section essentially composed of a cellulose derivative, saidtubular elementsbeing associated together in the form of 'abundle andbeing adhesivelyunited at their surfaces of contact with e cii otherwith the aid of a solution of a cellulose derivative, and an envelope"essentially composed of a cellulose derivative closely surrounding saidbundle of tubular elements, said envelope being adhesively united to thetubular elements at the points of contact therewith. with the aid of asolution of a'cellulose derivative. r

4. a light tubular structural unit comprising a plurality of parallellydisposed tubular elements of circular cross section essentially composedof a cellulose derivative reinforced with fibrous material, said tubularelements being associated together in the form of a bundle and 'beingadheslvely united at their surfaces of contact with eachother with theaid of a-soluticn of a cellulose derivative, and an envelope essentiallycomposed of a cellulose derivative reine forced with fibrous materialclosely surroundin said bundle of tubular elements, said envelope beingadhesively united to the tubular elements at the points of contacttherewith with the aid of a solution of a cellulose derivative.

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